Civil war

Civil war broke out when soldiers from Kiir's Dinka ethnic group disarmed and targeted troops of Machar's Nuer ethnic group. Machar and commanders loyal to him fled, and tens of thousands of people died in the civil war that followed.

A peace agreement signed in August collapsed and fighting continues in many parts of the country, despite both leaders joining a unity government two months ago.

Inside Story - South Sudan's forgotten crisis

The attack in Malakal threatens to deepen the conflict further. Leaders of the Shilluk ethnic group, the third largest tribe in the country who hail from Malakal, say that if they are not given their land back, fighting could ensue.

Another confidential investigation into the UN peacekeepers response during the Malakal raid found a "lack of a proactive mindset with regards to the protection of civilians" and "confusion with respect to command and control and lack of coordination".

A summary of the investigations, obtained by Al Jazeera, was sent to the UN Security Council. Sources say the full report contains damming information about peacekeepers failing to protect civilians.

A UN spokesperson said the full investigations will likely not be made public.

Peacekeepers fled

Ethiopian peacekeepers abandoned their posts during the attack, a UN military official in Malakal told Al Jazeera.

The official also said that Rwandan peacekeepers asked for permission in writing to fire their weapons as the base was under attack, even though peacekeepers are obligated to use force to protect civilians.

After a confrontation with South Sudanese government soldiers at a local airport during the attack, Rwandan peacekeepers fled their posts, according to an internal UN timeline obtained by Al Jazeera.

"The initial promise of these investigations appears threatened by the UN's unwillingness to present their full findings, either publicly or to the Security Council," Matt Wells, a senior adviser on peacekeeping at the Center for Civilians in Conflict, said.

"Attackers entered in the backyard of a UN base and proceeded to shoot and kill civilians and to systematically burn down large parts of the camp, as peacekeepers responded slowly and ineffectively."

In a statement, Doctors Without Boarders (MSF) said that the UN "failed in its duty to safeguard the people at the site and could have averted many fatalities".

The organisation, which lost two staff members during the attack, said that the UN blocked South Sudanese refugees from reaching safety when the base was under attack.

Many of the people who live inside the UN site in Malakal arrived shortly after South Sudan's civil war started in December of 2013. Although a peace agreement was signed in August, fighting continues across the country.

"It's very sad that something like 18 people, probably slightly more, have lost their lives" the spokeswoman for the UN Mission in South Sudan Ariane Quentier said in a radio interview after the attack.